Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method of controlling transmission power of an uplink control channel in a carrier aggregation system, and an apparatus using the method.
Related Art
Long term evolution (LTE) based on 3rd generation partnership project (3GPP) technical specification (TS) release 8 is a promising next-generation mobile communication standard.
Although a carrier having various bandwidths is provided in LTE, it is premised that communication is performed basically using one carrier.
Meanwhile, 3GPP LTE-advanced (A) which is an evolution of 3GPP LTE is under development. A carrier aggregation (CA) is a technique employed in the 3GPP LTE-A.
The CA uses a plurality of component carriers (CCs). The CC is defined with a center frequency and a bandwidth. One downlink (DL) CC or a pair of an uplink (UL) CC and a DL CC corresponds to one cell. When a user equipment receives a service by using a plurality of DL CCs, it can be said that the user equipment receives the service from a plurality of serving cells.
Conventionally, a user equipment to which a plurality of serving cells are configured can transmit an uplink control channel only through a specific cell called a primary cell among the plurality of serving cells. Therefore, it is specified that transmission power of the uplink control channel is determined by considering only the primary cell.
However, a future wireless communication system can transmit the uplink control channel also in different cells other than the primary cell among a plurality of aggregated cells. There is a need for a method and apparatus for controlling transmission power of the uplink control channel, which can be applied to the future wireless communication system.